(CCSP028) QTC PROLONGATION AND ITS ASSOCIATION WITH ELECTROLYTE ABNORMALITIES AND PSYCHOTROPIC DRUG USE AMONG PATIENTS WITH EATING DISORDERS

Background: Eating disorders, such as anorexia nervosa, often develop during adolescence and have high mortality rates. Sudden cardiac death in these patients has been associated with QTc interval prolongation which can generate fatal arrhythmias, including torsades de pointes. The mechanism and significance of extrinsic, rather than intrinsic, factors on QTc interval prolongation in eating disorder populations remain controversial. This study aimed to assess the relationship between QTc prolongation in pediatric eating disorder patients and extrinsic factors, such as known QTc-prolonging medications and electrolyte abnormalities to investigate whether the presence of an eating disorder alone is associated with an increased prevalence of QTc prolongation.

METHODS AND RESULTS: Electrocardiograms, serum electrolyte levels, and psychotropic medication usage were retrospectively analyzed from the charts of 264 pediatric eating disorder patients. The average patient age was 14.31 ± 1.92 (standard deviation) and 90.53% of patients were female. Descriptive statistics were used to assess QTc interval prolongation and its relationship with electrolyte abnormalities and psychopharmaceutical use. A statistical P-value of ≤ 0.05 was significant.

Of 264 patients, 227 had normal QTc intervals ( < 440 ms), while 37 had either borderline prolonged (440-460 ms) or prolonged (> 460 ms) intervals. The prevalence of QTc intervals exceeding 440ms in patients with normal electrolytes and without the use of QTc-prolonging psychotropics did not differ from the 8.7% of the general population with QTc prolongation (P = 0.59) (Montanez et al., 2004). Comparison of average serum electrolyte values between patients with normal QTc intervals and those with intervals above 440 ms revealed no significant differences for K+ (P = 0.077), Ca2+ (P = 0.18), or Mg2+ (P = 0.080). Of the 23 patients taking psychotropics, 3 patients had borderline prolonged QTc intervals while 5 patients had prolonged QTc intervals. The average QTc interval was greater for patients using QTc-prolonging psychotropics (P = 0.048) with a correlation between interval length and use of these agents (P = 0.000041). Averages of serum K+ and Ca2+ were not statistically different between patients with and without QTc-prolonging psychotropic usage, (K+ P = 0.82, Ca2+ P = 0.098), while average serum Mg2+ levels were statistically different between these groups (P = 0.023).

Conclusion: This study suggests that eating disorders alone do not innately prolong QTc intervals in pediatric populations. Instead, psychotropics appear to be a salient external factor in QTc prolongation and further investigations are necessary to analyze risk factors for sudden cardiac death in pediatric eating disorder patients.